The fine antigenic-specificity of A/PR8 influenza hemagglutinin-specific murine B and T-helper (TH) cells has been determined by use of viral recombinants and virus mutants with single amino acid mutations on the hemagglutinin (HA) molecule. The intention here is to prepare T-suppressor (TS) cell hybridomas against influenza, test these across the same panel of viruses or viral components, and compare their specificities to those of B and TH cells. Current evidence shows that B and TH-cells recognize different determinants on the HA molecule. If TS cells are triggered by regions of the HA which are distinct from those recognized by B and TH cells, selected antigenic determinats (protein fragments or peptides) may be administered in vivo to independently induce a single cell type. Depending on the choice of determinants made, deliberate expansion or suppression of the influenza HA response may be achieved. TS cells will also be analyzed for their ability to inhibit function of the already available TH cell clones. These TH clones were generated from mouse strains of H-2d and H-2b haplotypes and include influenza and ovalbumin specificities. Among influenza-specific clones are cells recognizing separate portions of the HA Molecule, as well as proteins of influenza other than HA. Each TS clone will be tested across the panel of TH cells to see which functional restrictions exist regarding MHC or antigenic fine specificity. TH - TS pair analysis should simplify understanding of the mechanism by which the T-suppressor signal is relayed to its individual target.